Method of making expansion joints



Patented Jan. 12, 1943 2,308,065 METHOD or MAKING EXPANSION :om'rsClarence B. Eckert, Englewood, N. 1., assignor to The CeiotexCorporation, Chicago, 111., a corporation of Delaware No Drawing.Application December 10, 1938, Serial No. 244,921

6 Claims. (Cl. 117 -140) This invention relates to improvements in thestructural building arts, and particularly relates to expansion jointmaterial used in connection with all kinds of structures, particularlyconcrete structures such as bridges. highways and the like.

Due to the fact that structures of this character have a tendency toexpand and contract with.

temperature changes, it is common practice to interpose expansion jointsat predetermined intervalsin the structures. Such expansion joints mustof necessity have certain resilient qualities and at the same time mustbe enduring and not readily affected by moisture or be subject todeterioration when exposed to the elements. "A practical joint shouldalso be one which is capable of being handled and put into place in anefllcie'nt and workmanlike style without an exceptional amount ofskilled eiiort. Furthermore, the joint material must'be one which can beproduced at a fairly reasonable cost.

Heretofore, expansion joint materials of this character have beenproduced and sold, but most.

of them have one or more objections in that some are subject to rapiddeterioration, and are not essentially waterproof, and are also somewhathard to install under the varying conditions encountered. Prior to myinvention, a further ob jection to the expansion joints previouslymanufacture'd has been that they have been made with I volatile solventswith the incumbent hazards of fires and explosion.

An object .of my invention. is to produce a highly emcient joint ofstandard building material so arranged and treated as to aiford all theadvantages desired in'joints of that character and eliminating to agreat degree all the disadvantages, such as theattendant hazards of fireand explosion.

Further objects of my invention are to produce I an expansion jointmaterial wihch is readily compressible, has a high degree of recovery,is nonextruding, and is resistant to the elements,- moisture, etc.

In preparing my improved expansion joint. there is preferably firstformed a vegetable fiber board, composed of finely comminuted vegetablefibers suitably felted together to form the board.

This board may be either formed independently or I may use certain formsof fiberboard already on the market, provided the same answer therequirements, as hereinafter set forth.

In the formation of this board, when the fibers arefelted, there areformed or left between the fibers, small interstices or voids. Thenatural resiliency of the finely comminuted fiber itself, in

conjunction with these voids lends to the board a certain resiliency sothat when compressed it will have an expansible action when the pressureis relieved therefrom. Thus the board so formed provides an admirablematerial in itself for use as an expansion joint in the respects abovediscussed. The density of the expansion joint mateiial is preferably0.235, however, it is within the scope of my invention 'thatmy novelmethod of making expansion joints may also be used with expansion jointmaterial having a, density as low as 0.120. The preferred range of thedensity of the expansion joint material when using my novel method ofmaking expansion joints and dependent upon the specific'use to which thematerial is utilized is therefore substantially within the range of thedensity of 0.120 to 0.270. However, I do not wish to limit myself tothis specific range of densities for expansion joint material, but Iwould like to use my novel method with all suitable types and densitiesof felted fibers the market or to be developed within the fut It isobvious that the fiber board described above without being suitablytreated would hardly be a suitable material for use in the respectsnoted for the reason that it might deteriorate ,when

exposed to the elements, and also would be apt to readily absorbmoisture, which would impair its resilient quality and also causedeterioration. I have found it necessary, therefore, in making use ofthis material to so treat it as to thoroughly incorporate thereinpreserving and waterproofing material. It is necessary, however, to soapply" the preserving and waterproofing material that while it wouldsubstantially encase and somewhat impregnate the individual fibers .ofthe mass it must not fill the interstices or air pockets in the mass ofthe, board itself, since if the interfiber spaces or voids are filledthe resiliency of the board is lost and its efilciency as an expansionjoint largely destroyed. a

I I, therefore, accomplished the various objects of my invention bytreatment of the board with the following materials and in the followingmannerz.

The base material for the expansion joint material preferably comprisesa relatively coarse 'which is manufactured by a process involvingfelting. of the fiber. from a water suspension of the fiber. Insulatingboard material which is a felted fiber productmanufactured fromrelatively coarse fibers derived from vegetative sources contains alarge proportion of interfiber air space provided by the relativelyloose fiber structure thereof, which characteristic imparts to the fibersheet an appreciable resiliency and relatively high heat insulatingvalue.

To prepare the base material for my novel expansion joint material andfor the particular purposes of this invention, the'sheet is firstpartially permeated or saturated with anasphaltic substance or with someother substance or compound having approximately the same generalcharacteristics. The saturant should be relatively firm at ordinarytemperatures such as are encountered in building constructions butshould not be brittle and could well comprise an appropriate pitch orthe like.

The saturant may be forced either by vacuum or by pressure treatment orby a combination thereof into and throughout the sheet material,however, in applying the saturant I prefer to use a dipping vat. Theapplication of this saturant to the base material of the expansion jointshould preferably be such that the fibers themselves are substantiallycoated and more or less saturated and a large part of, or substantiallyall of the interfiber or interior interstices or voids within the sheetare largely free of the saturating materials.

The saturant may be applied in any desired or convenient manner andinstead of being driven into the materials by either vacuum, orpressure, or by a combination of such treatment, it may be applied bythe submersion of the fiberboard in the saturant while such saturant isin a liquid state as by being maintained at an elevated tempera'turesuch that the saturant is liquid, or the saturant maybe applied as asolution preferably of asphaltum and a light petroleum oil. Should it bepreferable, it is to be understood that the base material for theexpansion joint material might have incorporated therein'during itsproces of manufacture sufficient of the asphaltic or other saturatingsubstance whereby the fibers of the base material are substantiallycoated and are firmly bound together, which last method of preparationwould involve a hot compression of the fiber sheet having the saturantdistributed For the saturation or permeation of a fiber in- 1 sulatingboard such as Celotex cane fiber insulating board of a density ofsubstantially 0.235 or within the range of densities of fiberboardranging from substantially 0.120 to 0.270, the preferred saturant is aVenezuelan residual asphalt of substantially the followingcharacteristics:

The above asphalt is heated to a temperature preferably from 360 to 390F. and the fiberboard or base material for the expansion joint materialis immersed therein, and on being held so immersed for a period of timeso that the fiber- I board will absorb the described asphalt to theextent of substantially 100% based on the dry weight of the fiberboardprior to immersion. In

scribed, it is to be understood that in the same general manner othersaturants can be incorporated into the fiberboard and generally speakingany asphalt having viscosity not exceeding 30 sec. furol at 375 F. maybe considered suitable providing, of course, it is raised to anappropriate temperature and that the fiberboard is held in such heatedasphalt for a period of time sufficient, as may be necessary, to obtainthe desired percentage of saturation. Among such asphalts are thosemadefrom petroleum cracking still residues (pressure tar pitches) whichat F. melting point will not exceed the viscosity just above stated.Blends of pressure tar pitches may be used with various residualasphalts of high melting point and high viscosity providing that thecombination is such that the resulting viscosity falls Within the limitsof the viscosity above given. Still other saturants such as equivalentcoal tars and oil tar pitches and blends may be used for saturation.

It is also within the scope of my invention that I may use a dippingbath composed preferably of asphaltum, and a flux, preferably a lightpetroleum oil. A suitable light petroleum oil which I prefer to use isknown as Bunker C fuel oil having the following specifications:

Gravity 14 A. P. I.

Furol viscosity 122 60 F. Pour point 40 F. Carbon residue Not to exceed9% B. S. & W Not to exceed .8% Sediment by extraction .5% Water bydistillation 1 I preferably use these with a portion thereof of eachconstituent so that the resultant saturant will readily penetrate thefiberboard. I heat the asphaltum to a fluid state and then add the oil.When the same are thoroughly mixed and in a perfect fluid state, andmaintaining the same well heated, I immerse the fiberboard therein andallow it to remain in the bath a sufiicient length of time for thefiberboard to be saturated from the surface thereof a definite distance,preferably /8", or for such a period of time that the fiberboard isimpregnated from its surfaces inwardly with the solution, fluid, orsaturant to the extent that the asphaltic contents of the finished boardwill vary from substantially 45% to 65% by weight of the finished board.

I have also found that it is possible to use a felted fiberboard havinga density of 0.200 within a few hours of the time that the feltedfiberboard has been made on themachine and dried, that is to say, itwould be still dry and warm at the time of dipping. It is obvious thatthe time of dipping necessary to give a satis actory penetration isdependent upon the density of the felted fiberboard. Using a standardsaturant such as I I have described, it has been found that a dippintime of from 15 to substantially 30 seconds in the saturant at atemperature of substantially 380 F. gave satisfactory results for /20.200 density felted fiberboard. During this time the asphalt penetratedimmediately to a depth of substantially at each surface, and an asphaltup-- take of approximately 100% of the original weight .of the board isobtained. I prefer to use dipping equipment comprising racks in whichthe boards are placed horizontally and dipped into the hot bath with acrane or other suitable apparatus. It is also within the scope of myinvention that the felted fiberboard may be fed continuously through thehot asphalt or other saturant in order to effect the necessary uptakeand penetration.

Although so far the description has been particularly with respect to/2" material, I have found that felted fiberboard material of variousthicknesses can be satisfactorily treated by my process. When using athicker material it is preferable to use a lower density feltedfiberboard, preferably having a density of not over 0.200 and have theboard as dry and warm as practical before dipping. However, with myprocess I have been able to suitably saturate felted fiberboards whichare substantially room temperatures. Higher density boards or boardsthat are not dry or which may have become cool before dipping requirelonger dipping time. In general, I have found that the /2" feltedfiberboard requires substantially a 5 second dip, board a 30 second dip,and 1" felted fiberboard substantially 2 minutes. The asphaltic contentof the finished board used for expansion joint material will vary fromsubstantially 45% to 65% by weight of the board.

After the felted fiberboards are removed from I the dipping bath, theexcess of saturant is preferably wiped therefrom by scraping orsqueezing with rolls. The partly impregnated felted fiberboard partlysaturated, inwardly from its surfaces, is then heated or baked to securesuitable penetration of the saturant throughout the board or sheet. Toeffect the necessary penetration I prefer to use hot stacks in place ofan oven or direct heating of the felted fiber materials. With the hotstack method, the heat picked up by the and substantially no odor.

desired for the use to which the felted fiber material treated by myprocess is'to be utilized.

Although I prefer to fiat pile the felted fiber material, after it hasbeen removed from the dipping bath in the hot stacks, it is also withinthe scope of my invention that the dipped board when stacked and piledmay be stacked on edge. It is preferable in piling the board, that theedges or surfaces that were down in the dipping vat shall be uppermostin the hot'stack.

The preferred characteristics of the expansion joint material formed andprocessed as described above are, a resiliency of not less thansubstantially 70%, a twenty-four hour water absorption not exceeding12%, per cent asphalt by extraction within the range of substantially45% to 65%, It should also be adapted to suitably bond to concrete. Thetest for resiliency is preferably determined on a sample 4" x 5" bycompressing it to one-half its original thickness five times, allowingan interval of 90 seconds between pressing and seconds under pressure.The ratio of the final expanded thickness taken one hour after the lastpressing to the original thickness isthe percent resiliency whenmultiplied by 100. It is preferable that the loss of weight should notbe over 2%. The weight of the sample is taken before and after theresiliency test and the loss expressed as percent of original feltedfiberboard during the dipping process is utilized. 'In using thismethod, I prefer to use a hot dry board althoughit is obvious that aboard at room temperature may-be used. Inusing this method it isnecessary to use a sufficiently fluid mixture of asphalt andoil and/or asuitable saturant to obtain complete penetration.

The felted fiber material after it leaves the apparatus for removing theexcess saturant is close piled in a stack for several days. By thistreatment due to the effect of heat and lapse of time, the saturant willdistribute itself substantially uniformly throughout the feltedmaterial, at least to a point where there is substantially nounsaturated material showing when a' sample is broken. It is preferableto suitably insulate the stack, and preferably the edges thereof, as bycovering it with a heat insulation material to prevent heat lossestherefrom. If it is necessary to maintain the required temperature ofthe hot stack, heat may be suitably supplied thereto. 'This process iscalled dog-housing. .The'felted fiberboards are left in the hot stacksfor substantially twentyfour hours more or less, or until thepenetration or dispersion of asphalt or other saturant as disclosed issubstantially complete, and the boards 'arethen placed in cooling racksuntil sufliciently fourhours, it is witliiirthe scope of my inventionthat the felted fiber material may be hot stacked for a period of timenecessary-to obtain the penetration necessary or to obtain thecharacteristics weight. The pressure for compression should preferablynot be over 425 lbs. per square inch. In the foregoing specification ofpreferred characteristics, the compression pressure was substantially140 lbs. per square inch; It is also preferable that the expansion jointmaterial shall show no tendency to delaminate or disintegrate whengiventhe hydrochloric acid test. For convenience in handling the finishedexpansion joint material, it should not be sticky.

By my novel method of substantially impreg-- nating surface portions ofthe-felted fiber material and then by heating, baking, or preferably byhot stacking, causing the impregnating substance to disperse orpenetrate throughout the fiber material, I am able to suitablyimpregnate into and around the individual fibers of the mass theasphaltum, the asphaltum and oil, or other suitable saturants. The hotstacking of the partially impregnated felted fiberboard by bringingabout the dispersion of the saturant leaves the interstices or air voidsin the board substantially unimpaired, so that the resiliency of theboard is still present, although the fiber of the material is thoroughlywaterproofed and preserved against deterioration. when a saturant ofasphaltum and light oil is used, the light oil remaining with theasphaltum tends to keep the asphaltum' in the mass in a softenedcondition rather than allowing it to become dry and hard, which mightcause it to become brittle and breakable in use.

The material thus formed may be readily handled and cut up into varioussizes and shapes for use as expansion joint material, due to its beingin boardform and readily capable of being cut, and handled at will; and,it has an inherent stability so that when placed in position it willremain intact without any tendency to slump or deform as is the commonobjection to certain other types of expansion joints. I

From the foregoing description, it .will be readily seen that.I have''produced a material for use as an-expansion joint which has all theadvantages necessary and none of the disadvan tages referred to.

Now I have herein set forth the preferred 7 materials used in theconstruction of the joint, it is to be understood that I do not wish tolimit myself to the use of any particular type of vegetable fiber or anyparticular. waterproofing and preserving materials, the above beingrecited merely as the preferred material desired to 'be used in thisregard, although in actual practice I would, of course, reserve theright to use any -fourth of the thickness of the felted fiber board,

the fiber board removed from the bath and the saturant caused in part tomigrate from the substantially saturated portion of the board into andthroughout the unsaturated portion of the board bymaintaining the boardat an elevated temperature.

2. The method of treating a felted fiber board of substantially one-halfinch to about one inch in thickness, and of a density of between 0.102and 0.207 which comprises establishing a hot dipping bath of anasphaltic saturant maintained at the temperature of between about 360 F.to 390 F., immersing the fiber board in the bath-for a time of fromabout thirty seconds to about two minutes and substantially impregnatingthe fiber board with the saturant in the amount of from about to 100% ofthe weight of the dry fiber board being treated, but to only a limiteddepth from the surfaces thereof, the fiber board removed from the bathand any excess saturant removed from the surface thereof, the saturantcontained in the substantially saturated portion of the board caused tobe distributed substantially uniformly throughout the entire board byholding the board at a temperature about that of the temperature ofdipping.

3. The method of treating a felted fiber board as defined in claim 1,wherein the limited impregnation of the fiber board involves theaddition to the board of the asphaltic saturant to the extent of frombetween about 45% to 100% of the dry weight of the fiber board.

4. The method of treating a felted fiber board as defined in claim 1 andwherein the asphaltic saturant is composed of asphalt and a flux oil.

5. As a new article of manufacture, a product produced in accordancewith the method of claim 1.

6. As a new article of manufacture, a product produced in accordancewith the method of claim 1, having a resiliency of not substantiallyless than a twenty-four hour water absorption not substantially inexcess of 12%, and containingv asphalt by extraction not in excess ofbut preferably in the amount of between about 45% to 65%, the producthaving substantially no odor.

CLARENCE R. ECKERT.

